Apparatus and method for gait training

ABSTRACT

Arrangement for training the gait, comprising a predetermined walking surface, kick-on location sensing means for determining actual kick-on locations where a patient kicks his feet on the walking surface, which kick-on sensing means are associated to the walking surface, a training program memory for storing a gait training program which comprises data for predetermining a sequence of instructed kick-on locations for the feet of the patient on the walking surface, a display apparatus for displaying images which show the instructed kick-on locations, and a display synchronizing apparatus, which at its input side is connected to the training program memory and to the kick-on location sensing means and at its output side with the display apparatus to output data of the kick-on location sensing means in such manner that the display of the instructed kick-on locations is continuously adapted to sensed actual kick-on locations.

The present invention relates to an arrangement and a method fortraining the gait.

Prior art apparatus for the detection of pressure and forcedistributions which are disclosed, for example, in DE 36 42 088 C2 andDE 25 29 475 C3, can be used as platforms for biomechanical gaitanalysis, which is being used for examining and analyzing the gait of avertebrate, especially of a human being. There is the drawback, however,that only one single step and one single flexing action of the foot canbe recorded. To obtain a natural gait behavior it is necessary, however,to record the gait over a longer time period.

Likewise, apparatus and methods for the gait analysis are well-known,which offer the possibility of such registration and analysis and whichmake use of a treadmill. Reference is here made, for example, to DE 4027 317 C1 or U.S. Pat. No. 6,010,465 A.

In R. Kram and A. J. Powell: “A treadmill-mounted force platform” Appl.Physiol. 67 (4): 1692-1698 (1989), an apparatus is being described aspreviously disclosed, wherein a treadmill belt is drawn over a measuringplatform or measuring surface, respectively, thereby permitting acontinuous detection of forces applied by a patient's feet.

Further known is the use of display devices, such as display screens, intreadmill systems.

Known from EP 1 145 1682 A2 are a rehabilitation apparatus and methodbased on the treadmill technology, wherein an adaptation of the functionof the treadmill to the current status of a patient's walking or runningability to be restored is provided. Specifically, the speed of thetreadmill is adapted to a personal step cycle of the user and, at thesame time, the apparatus is to give the user a feedback. In a specificembodiment, also the detection of pressure forces exerted during a stepas well as the analysis thereof are provided as part of an overallprogram. The publication also describes the use of a display screen inconnection with a keyboard, to display the footprints generated on thetreadmill belt and to adjust treadmill belt parameters on the basis ofthis display.

U.S. Pat. No. 6,231,527 B1 likewise discloses the use of a displayscreen in a treadmill apparatus for use in sports medicine andrehabilitation, wherein the images of different cameras can bedisplayed, which record the movements of the sportsman/patient on thetreadmill.

Also EP 2 352 462 and WO 2010/057552 of the applicant describes atreadmill system for use in sports medicine and rehabilitation based onan image display technology, which additionally allows that pressuredistribution patterns generated by a person walking on the treadmill arerecorded and analyzed synchronously with the displayed images.

The invention is based on the object to provide a further improvedapparatus of the last-mentioned type, which is particularly suited forsports-medical and rehabilitation purposes. It is one aim to furtherdevelop the system to obtain a flexibly usable training/therapyapparatus while simultaneously increasing the user acceptance as well asthe physiotherapeutic effect.

This object is solved, according to its device aspects, with anarrangement according to the features of claim 1, and in its methodaspects, with a method according to the features of claim 12. Usefulimprovements of the inventive thought are each defined in the dependentclaims.

The invention includes the idea, not only to rigidly prescribe a stepsequence as his training program to an exercising patient, but rather totake his training status and his current efforts into account.Furthermore, the invention includes the idea that, for this purpose, thesteps of the patient or, more precisely, the locations (points) where heactually sets (kicks) his feet onto the walking surface (subsequentlycalled sensed kick-on locations) be detected and taken into account whenoffering the training program to him. This leads to the further ideathat an image display of prescribed steps or, more precisely, prescribedkick-on locations of the feet of the patient (subsequently calledinstructed kick-on locations) be synchronized to the detected actualsteps (sensed kick-on locations).

Hence, under device aspects an arrangement is being proposed whichcomprises, besides a predetermined walking surface (which can existindependently from the measuring arrangement), kick-on location sensingmeans for determining actual kick-on locations where a patient kicks hisfeet on the walking surface, which kick-on sensing means are associatedto the walking surface, a training program memory for storing a gaittraining program which comprises data for predetermining a sequence ofinstructed kick-on locations for the feet of the patient, a displayapparatus for displaying images which show the instructed kick-onlocations, and a display synchronizing apparatus, which at its inputside is connected to the training program memory and to the kick-onlocation sensing means.

The proposed solution has major advantages: It is a drawback of priorart arrangements that the patient (who is typically heavily handicapped)must initially “synchronize” for the measurements, i.e. must take carethat his foot meets a projected image. Since he starts from an arbitraryposition, this is very difficult. Once he has met a projected image withhis foot, he must continuously correct each respective subsequent step,once he has made a mistake (i.e. not appropriately met the prescribedlocation). This correction step, however, is not that step which shouldbe trained but is shorter or longer or possibly includes an increased ordecreased step breadth (lateral distance of the feet) or a rotation ofthe foot. This is even more difficult, if the image is not projectedonto the treadmill belt itself but onto a screen.

In the invention, mistakes in setting the feet onto the surface are nolonger important, since the system always automatically outputspredetermined steps which are to be learned. Herein, the step width(step length) is an important parameter; besides this the proposedsolution can also adapt the timely aspects of the gait training programto the actual status of a specific patient.

The measuring means for determining the current position can preferablybe implemented with the well-known arrangement of a matrix-type pressuredistribution sensor plate or pressure switch plate. However,alternatively measuring systems based on light barrier arrays of thereflective or transmissive type, 2D or 3D cameras etc. can be used.Preferably the arrangement is operated on a treadmill. If the images areprojected directly onto the measuring surface, the arrangement can evenbe used on an fixed walking surface, which optionally can be providedwith exchangeable surfaces and/or specific obstacles.

In a further embodiment of the invention, a sequence of sensed kick-onlocations is sequentially detected, in a timely resolved manner, and theimage display is being synchronized for displaying the instructedkick-on locations in adaptation to the sequence of the sensed kick-onlocations. Under device aspects, hence, the kick-on location sensingmeans comprise a memory unit for, in a timely resolved manner, storing asequence of sequentially sensed actual kick-on locations and the displaysynchronizing apparatus is adapted for loading the sequence and foradapting the instructed kick-on locations to be displayed to the sensedsequence. Alternatively, it is proposed that one or more gait parametersof the patient, which have been determined based on previously detectedkick-on locations, can be stored and the display synchronizing apparatusbe operated on the basis of an evaluation of this parameter orparameters.

In a further embodiment, the arrangement comprises a feedback unit fordetecting contacts of the walking surface by the subject at the placewhere predetermined image elements are displayed, or at places where nopredetermined image element is displayed, and for outputting a warningor information signal in response thereto. Additionally or evenindependent from the latter embodiment, a user guide unit for the visualand/or audible output of display-accompanying instructions, particularlyby means of earphones and/or text projections by the display unit, canbe provided. In addition to the inventive adaptation of the trainingprogram to the actual step sequence of the patient, herewith asupplementary support can be provided to the patient's training.

In the framework of the invention, several algorithms can be implementedfor taking the collumnly sensed kick-on locations of the feet of thepatient or gait parameters derived therefrom into account, for adaptingthe training program to the real situation of the patient. An embodimentwhich appears to be preferred, includes a moving adaptation of apredetermined instructed step width to a sensed step width. Additionallyor, should the situation arise, alternatively a step-wise adaptationwith respect to the step width or a moving or step-wise adaptation withrespect to one or more other gait parameters can be implemented,specifically regarding the step frequence or lateral distance of thefeet.

The implementation of training or rehabilitation programs can be asfollows: Initially, the patient walks in accordance with his accustomedwalking style. By means of the pressure sensor matrix integrated in thetreadmill the characteristic gait parameters are detected, especiallythe length of the steps, the track width, the foot rotation angle orapplied force values. These parameters may then be used as startingvalues for the training. Based on this setting, the patterns projectedonto the treadmill belt are then automatically adapted to the targetvalue desired by the therapist within one training process. Thealteration of the values may be linear, exponential or be accomplishedwith any other mathematical function. Subsequently, an automaticanalysis based on a target-performance comparison can be performed, i.e.it is checked how good the patient was at complying with the defaults.If the patient is to vary the applied force in partial regions of thefoot or of the whole foot he is instructed by an acoustic signal or avoice output, for example, an instruction to put more or less weight ona foot.

In a specific embodiment predefined step widths or breadths can besteadily varied (e.g. increased) during a training process so as to makethe patient slowly approach the training goals. This is accomplished byan embodiment in which the display process controller comprises aprogram memory for storing a plurality of predetermined displayprocesses and/or speed and/or relative position adjusting means foradjusting the speed of a display process and for predefining relativepositions between image elements of a display. Advantages and usefulfeatures of the invention will be explained in the following descriptionof preferred embodiments by means of figures. In the figures:

FIG. 1 shows a schematic representation of a first embodiment of theinvention,

FIG. 2 shows a schematic representation of a second embodiment of theinvention,

FIG. 3 shows a detailed view of another embodiment,

FIG. 4 shows a detailed view of another embodiment, and

FIG. 5 shows an image as may be provided during a training program onthe walking surface of the arrangement.

FIG. 1 shows a treadmill training system 1, comprising a treadmill belt2 b running over two rollers 2 a, underneath the upper surface of which,which is used by the user as walking surface 2 c, a pressure detectionplate 3 with a high spatial resolution and having a plurality of (notindividually designated) pressure sensors is provided, which pressuresensors are arranged in a matrix-type manner and detect pressuredetection images generated by the user as he steps on the treadmill. Oneof the two rollers 2 a is driven and pulls the treadmill belt 2 b at apredetermined speed, which is adjusted by a processing and control unit4 of the arrangement and by a speed controller 5. Moreover, it ispossible to adjust an inclination of the treadmill as a whole accordingto need or, optionally, slightly raise only the front portion thereof bymeans of a suited inclination actuator 6, which can likewise receiveinterference signals from the processing and control unit 4 (this ismerely symbolically illustrated in the figure).

In the embodiment illustrated in FIG. 1, which is strongly simplified,signals characterizing the adjusted speed value of the treadmill arereported back from the speed controller 5 to the processing and controlunit 4, where they serve the synchronization of an image displayed onthe walking surface 2 c by means of a projector (laser beamer) 7, theimage being generated from prestored image elements and/or imagesequences (see below).

The image is controlled on the basis of the speed signals in such a waythat—especially in connection with another specific embodiment describedbelow—the user is presented an altogether harmonious simulation of awalking environment, preferably combined with the insertion of markingsto be touched by the feet and/or with the simulation of obstacles to beclimbed over or avoided. Diverging from the representation in thefigure, the actual speed of the treadmill can also be detected by asuitable (non-illustrated) sensor system, and the measured value can besupplied to the processing and control unit 4 in order to obtain a(virtually feedback) process control of the image display andsynchronized analysis of the pressure distribution patterns.

It is shown in the figure that the projector 7 is fixed to a wall holder7 a in an adjustable manner with respect to angles, so that thedirection of the projection encloses with the plane of the treadmill avariable angle. In order to avoid distortions of the images or imageelements, which are provided by the processing and control unit 4, dueto the acute angle of projection an image signal distortion corrector 7b is connected upstream of the projector 7. This distortion corrector 7b can operate dependent on the actual angular position of the projector7 in the holder 7 a, which is not shown in the figures, however, forreasons of clarity. Moreover, in order to round up the user interface anaudio stage 8 is provided (here symbolized as a loudspeaker), by meansof which the person doing the workout can receive additional acoustictraining instructions. The audio stage 8 can also be realized, forexample, bidirectionally in form of a headset, so that the person doingthe workout can give an acoustic feedback (e.g. an acknowledgment ofreceived instructions or answers to questions he is asked).

For performing training tasks on the treadmill system it may be ofinterest to detect the lifting height of the feet from the belt, forexample, when the subject is to climb over a virtual obstacle. Inanother embodiment the subject therefore has a sensor 9 attached to eachof his feet, the signals of which can be detected by means of a(non-illustrated) position detection sensing system, which is known perse, so as to draw conclusions on the position or the height of the feet,respectively. Preferably, the sensors are operated time-synchronizedwith the sensors of the pressure distribution matrix. If appropriate, aprecise time synchronization can be generated by means of an infrared orradio signal or by a detection of the moment when the feet contact thebelt.

The sensors 9 may be designed as acceleration sensors or multi-axisacceleration sensors and, if appropriate, are wirelessly connected tothe analyzing computer 4. The position of the feet can be calculatedfrom the acceleration signals, especially if the time and positiondependence of the pressure distribution patterns can be additionallyincluded in the calculation. In extended arrangements, inertial sensorsystems may be employed, in which gyroscopes or sensors for detectingthe earth magnetic field are used additionally. Of course, such sensorscan also be attached to other body sections, so that the movement of thecomplete lower extremities or of the whole body can be measured andrepresented. However, the sensors 9 may also be operated in accordancewith other measuring principles, e.g. on the basis of active or passivelight markers recorded by stationary cameras, magnetic field sensors, orsensors emitting or receiving ultrasonic waves to or from stationaryreceivers and determining the position of the feet from the propagationtime of the sound.

The pressure sensors of the pressure detection plate may optionally beprovided with an analog or—according to a simpler and more inexpensiveembodiment—a digital response characteristic (on/off characteristic).Both options are eligible for certain applications, and the systemdesigner will choose one of the options in accordance with the primaryuse requirements.

FIG. 2 shows a modification of the arrangement shown in FIG. 1 anddescribed above. Insofar as the same components of the latter areemployed, they are designated with the same reference numbers used inFIG. 1 and will not be explained again below.

The essential modification consists in using a large-surfaceelectro-optical touchscreen 7′ as display device instead of a projector.The upper surface of the touchscreen defines a display surface 2 c′located, in use, underneath the upper section of the endless belt 2 b.At the same time, the touchscreen defines a novel pressure detectionplate 3′. According to a modified version of the touchscreen principle,and in the light of the actual costs for the arrangement, this combineddisplay/pressure detection device may be replaced by a matrix-typealternating arrangement of a plurality of smaller electro-opticaldisplay elements (e.g. LCD displays) and respective adjacent smallerpressure detection plates, or a flexible display screen insensitive topressure (e.g. of the OLED type) may be placed over a normal pressuredetection plate.

In all cases the endless belt (2 b) is to be formed of a transparentmaterial, at least in the central portion of its lateral extension, inorder to allow the person doing the workout a perception of the imagesdisplayed on the display surface 2 c′.

FIG. 3 shows a detailed representation of essential components of theprocessing and control unit 4 of the arrangement illustrated in FIG. 1or 2. Not included is here the image signal distortion correctorseparately shown in FIG. 1, which is used only in an embodiment of thearrangement where the projector is inclined relative to the treadmill.

In a display control part 4A the processing and control unit 4 comprisesan image element storing unit 41 and a video memory 42, with an imageelement mixer 43 and finally a video image element mixer 44 forgenerating image sequences with predetermined image element insertionsbeing connected downstream thereof. In addition, it is symbolicallyshown that both mixers 43, 44 can moreover be influenced by controlsignals of a random generator 45. Also, a display process controller 46is connected downstream of the second mixer 44, which is assigned aprocess program memory 47 and a synchronizing unit 48. An image elementposition controller 49 is connected, in terms of control signals, to theimage element mixer 43 and acts on the same so as to vary relativepositions of image elements in the ultimate representation.

The synchronizing unit 48 can be influenced by signals of the speedcontroller 5 of the treadmill (not shown in this figure). Primarily,however, the coordinate values of sensed kick-on locations of the feetof the patient are input into the synchronizing unit, which coordinatesor (as mentioned further above) calculated from the pressure sensingimages which are created on the pressure distribution plate 3 accordingto FIG. 1 by the feet of the patient. Additionally, the signals ofsensors 9 in FIG. 1 can (what is not shown in the figure) input into thesynchronizing unit 48 as further input signals. This serves for finallysynchronizing the display, in particular as far as it shows instructedkick-on locations for the feet of the patient, to the speed of thetreadmill as well as to the sensed kick-on locations of the feet of thepatient and optionally to further motional parameters of the feet of thepatient. Regarding the adaptation of the displays presented to thepatient to his actual motions, the display process controller 46 and thesynchronizing unit 48 can together be considered as a displaysynchronizing apparatus of the arrangement.

At the same time, these signals are supplied to a system control unit 50of the arrangement, which synchronizes the different control proceduresof the display and analysis functions and performs necessary adaptationsof the data streams and data formats. In the figure this is symbolizedby the double arrows pointing to the display control part 4A and theanalyzing section 4B.

Moreover, the final image signal provided at the output of the displayprocess controller and, on the other hand, the (space-time-resolved)output signal of the pressure distribution plate 3 are supplied to theanalyzing section 4B. The output signal of the pressure distributionplate 3 is freed from interference signals and artefacts in a pressuresignal preprocessing stage 51, is synchronized with the image signals interms of time in a pressure signal time adaptation stage 52 and in termsof space in a pressure signal position adaptation stage 53, and isprocessed in a training analysis stage (main processing stage) 53 on thebasis of a predetermined training analysis program, and the results areoutputted on a separate display unit 10 of the therapist. Moreover, theycan be processed—together with instructions inputted via an input unit11 of the therapist—to instructions for the person doing the workout ina user guide stage 54, which instructions are outputted by the displayunit 7 or T assigned to the person doing the workout and, optionally, bythe audio stage 8.

FIG. 4 shows in a detail view parts of a further arrangement 1′according to an embodiment of the invention, which parts are essentialto the implementation of the present invention. These are a fixed,limited walking surface 2′ to which surface—immediately above thesurface—as core component of a kick-on location sensing apparatus alaser light barrier 12 is associated, which means can use a laterallyspread-out laser beam or which can work according to the principle ofmultiple reflections and which, by these means, is modified to become alarge-area light barrier. Once a user (patient), within the area ofdetection of this light barrier, sets (kicks) his feet onto the walkingsurface, this will be detected by means of the light barrier byproviding plural single (commercially available and inexpensive) lightbarriers or by using means with high positional resolution the kick-onlocation (actual kick-on location) of the feet of the patient can bedetected. The coordinates of the kick-on locations which have beendetected over a predetermined time period can be stored in a kick-onlocation storing unit 13, which is connected to the output of the laserlight barrier means 12, in a time-dependent manner. This storing unitcan work according to the FIFO-principle and, in this way, beautomatically updated.

The training program memory 14 is provided for storing training programsfor training the gait, which programs can in particular be specified bya predetermined step sequence and width and optionally furtherparameters, such as the lateral distance of the feet. The kick-onstoring unit 13 (as part of the kick-on sensing apparatus) as well asthe training program memory 14 are connected to inputs of a displaysynchronizing apparatus 15 for synchronizing gait instructions which areshown to the patient with his actual motions.

The display synchronizing apparatus 15 comprises a calculating stage 15a for calculating relevant gait parameters from a timely sequence ofsensed kick-on locations loaded from the kick-on location memory 13, aswell as an adaptation stage 15 b for adapting a predetermined stepsequence, which is being loaded from the training program memory, to thegait parameters of the patient. The synchronizing apparatus outputs asequence of coordinates of instructed kick-on locations for the furthergait on the walking surface 2′, which sequence is adapted to the actualmotions of the patient, and this is done by means of a display controlunit 16 of a large screen 17 onto which the patient looks during hisgait training.

Exemplifying an image to be provided for the person doing the workout onthe walking surface FIG. 5 shows (in a simplified manner) a series offootprints f′, combined with ground features A (puddle or “soft” spot)and B (stone or hard elevation). It follows from the above explanationsthat the impression of these obstacles is not only conveyed by a visualperception, but in combination therewith also by a tactile perception,which is realized by means of an array of actuators in the walkingsurface of the type shown in FIG. 4.

The realization of the invention is not limited to the above-describedexamples, but is also possible in a plurality of modifications withinthe framework of the competent action of the skilled person.

1. Arrangement for training the gait, comprising: a predeterminedwalking surface, kick-on location sensing means for determining actualkick-on locations where a patient kicks his feet on the walking surface,which kick-on sensing means are associated to the walking surface, atraining program memory for storing a gait training program whichcomprises data for predetermining a sequence of instructed kick-onlocations for the feet of the patient on the walking surface, a displayapparatus for displaying images which show the instructed kick-onlocations, and a display synchronizing apparatus, which at its inputside is connected to the training program memory and to the kick-onlocation sensing means and at its output side with the display apparatusto output data of the kick-on location sensing means in such manner thatthe display of the instructed kick-on locations is continuously adaptedto sensed actual kick-on locations.
 2. Arrangement of claim 1, whereinthe kick-on location sensing means comprise a memory unit for, in atimely resolved manner, storing a sequence of sequentially sensed actualkick-on locations or a parameter which characterizes such sequence, andthe display synchronizing apparatus is adapted for loading the sequenceand for adapting the instructed kick-on locations to be displayed to thesensed sequence.
 3. Arrangement of claim 1, wherein the displayapparatus comprises a display or projection screen which is positionedabove the walking surface.
 4. Arrangement of claim 3, wherein thedisplay apparatus comprises an image projector and the walking surfaceis adapted to serve as projection screen.
 5. Arrangement of claim 1,comprising a feedback unit for detecting contacts of the walking surfaceby the subject at the place where predetermined image elements aredisplayed, or at places where no predetermined image element isdisplayed, and for outputting a warning or information signal inresponse thereto.
 6. Arrangement of claim 1, comprising a user guideunit for the visual and/or audible output of display-accompanyinginstructions, particularly by means of earphones and/or text projectionsonto the area of the walking surface.
 7. Arrangement of claim 1,comprising an endless belt guided over at least two rollers and servingas a treadmill, the one surface of which serves as the walking surface.8. Arrangement of claim 1, wherein the kick-on location sensing meanscomprise: a force measurement plate located underneath the walkingsurface, which is provided with a plurality of pressure/force sensors onthe side facing the endless belt, an analyzing unit connected, on theinput side, to the pressure/force sensors, which detects pressuredistributions processing unit connected on the input side, to theanalyzing unit, which determines the actual kick-on locations from thepressure distributions.
 9. Arrangement of claim 1, wherein the kick-onlocation sensing means comprises optical detector means for detectingthe position of the feet of the patient at the point of time ofkicking-on to the walking surface, in particular a camera or lightbarrier unit.
 10. Arrangement of claim 1, wherein the data concerningthe determination of the sequence of instructed kick-on locationscomprise an instructed step width and/or wherein the parameter forcharacterizing the sequence of instructed kick-on locations is an actualstep width.
 11. Arrangement of claim 10, wherein in the displaysynchronizing apparatus an algorithm for movingly adapting apre-programmed instructed step width to a sensed step width isimplemented.
 12. Method for training the gait of a patient on apredetermined walking surface, wherein by means of kick-on locationsensing means which are associated to the walking surface actual kick-onlocations are sensed, where the patient kicks his feet onto the walkingsurface, according to a predetermined training program a sequence ofpredetermined instructed kick-on locations of the feet of the patient onthe walking surface is calculated and by means of a display apparatusimages are displayed to the patient, which show instructed kick-onlocations of his feet, wherein the display is continuously synchronizedfor showing instructed kick-on locations which are adapted to the sensedkick-on locations which have been detected by means of the kick-onlocation sensing means.
 13. Method of claim 12, wherein, in timelyresolved manner, a sequence of actual kick-on locations is beingsequentially detected and the synchronization of the display for showingthe adapted instructed kick-on locations is made in response to thesequence of actual kick-on locations.
 14. Method of claim 12, whereinthe synchronization of the displayed instructed kick-on locations to thesensed kick-on locations comprises movingly adapting a predeterminedinstructed step width to a sensed step width of the patient.
 15. Methodof claim 12, wherein the sensing of the actual kick-on locations of thefeet of the patient onto the walking surface comprises an opticaldetection, in particular by means of a camera or light barrier, or isbased on the detection of pressure distribution images of the feet ofthe patient on a matrix-type pressure sensor arrangement locatedunderneath the walking surface.